This invention relates to air data sensors, and, more particularly, to a canard based air speed, angle of attack and sideslip measurement system.
Future aircraft will require controlled highly instantaneous 3-dimensional maneuvers in the post stall regime. Such maneuvers require air data parameters to be measured throughout the flight regime. Prior art solutions to air data measurements in the post stall regime, specifically measurements of angle of attack and sideslip, typically use a differential pressure probe, this approach does not measure air data parameters sufficiently accurately at high angle of attack. Prior art systems induce unacceptable amounts of pneumatic lag, and/or an additional appendage jutting into the air stream, which adversely affect aircraft performance.
FIG. 1 shows the situation of two aircraft maneuvering for position. Aircraft 1 does not incorporate a canard in the forward part of the fuselage. Aircraft 2 does incorporate a canard 10. To maneuver for an advantageous position aircraft 1 must perform a relatively wide sweeping motion where aircraft 2 can use the canard 10 to enter the post stall region and quickly make a turn, out maneuvering aircraft 1. The advantage of a canard, that of quick turning and supermaneuverability, dictates the need for a high angle of attack and side slip measurement system.
FIG. 2 shows graphically the greatly improved turning radius of a canard equipped aircraft as compared to a conventional aircraft. Arrow 12 on plot B indicates the aircraft turning tightly using the stall canard technique and arrow 14 on plot A indicates the aircraft using the conventional flight turn technique. The canard equipped aircraft thus enjoys a greater freedom of motion.
An air data parameter measurement system according to the invention can be advantageously employed in a aircraft whose post stall maneuvering capabilities exceed those of conventional aircraft which typically have a 20.degree. angle of attack capability. In such an application the ability to measure air speed, angle of attack and side slip is crucial. Such supermaneuverable aircraft will be able to perform small radius turns with a 90.degree. angle of attack capability. Such aircraft will also be able to fly at super high angles-of-attack in the post stall regime safely because accurate side slip measurements will be available to warn of excessive yaw.